The invention relates to an unfoamed foil of a thermoplastic resin capable of serving as an adhesive when softened and adapted for use in the manufacture of laminates.
Such foils are known for adhesive purposes. They belong to the so-called hot melt adhesives. This type of glued joint is important in a great many fields of the art, not only as a direct joint but also as a further protection for a screwed or bolted joint or for fillingly or structurally sealing a riveted or spot-welded plate joint.
In many fields, e.g., in the construction of trucks and in the ship- and aircraft-building industries, plating structures, assemblies of plates, shells, ribs, frames and stiffeners are realized in a laborious and labor-intensive manner by means of riveting or spot-welding. These discrete stiffenings and reinforcements can be thought of as expanded in the form of sandwich plating structures, two relatively thin plates of fiber reinforced plastic or metal with an intermediate light core material of foam or honeycomb material. Consequently, attempts have also been made to replace the plating structures by this type of laminates. This technique is often applied in the aircraft-building industry. For assembling purposes this requires massive edges. With these plates manufactured by means of an autoclave or a hot press, this generally occurs by applying separate thick laminates in the laminating phase. According to another technique pieces of impregnated fabric were manually put on a table and cut out, followed by applying the honeycomb as well as a covering layer thereon and filling the edges. This is of course extremely labor-intensive and must further be followed by a more difficult treatment cycle at elevated temperature and pressure. A more recent and improved development is that the honeycomb is coated with an adhesive, followed by assembling the whole. It is difficult, however, to obtain a homogeneous coating of adhesive. As far as a solvent is used, the coating must be dried.
European patent application 212,970 discloses an adhesive tape comprising an elastomer, a crosslinker and optionally a blowing agent. This tape is especially useful for isolation, such as sonic isolation.